The prevailing El Nino conditions over the tropical Pacific could be unprecedented in strength, the World Meteorological Organization (WMO) said on Wednesday (October 21, 2026) in its new seasonal climate outlook.

It stated that sea surface temperatures in the tropical Pacific may rise to 3.8 degrees Celsius above average during November 2026 to January 2027.

The WMO declares an El Nino when the sea surface temperature anomaly in this region is 0.5 degrees Celsius.

In a statement, WMO Secretary-General Celeste Saulo said, "This is literally off the monitoring charts that we have used for the past four decades. El Nino will peak towards the end of 2026 but its impacts will be felt long after that."

El Nino is one of the three phases of the El Nino Southern Oscillation (ENSO) — a climate phenomenon characterised by changes in sea temperatures along the central and eastern tropical Pacific Ocean, accompanied by fluctuations in the atmosphere overhead.

While El Nino is known to have a warming effect over the planet, its opposite phase, La Nina, usually results in a cooling effect. ENSO also has a neutral phase.

A very strong El Nino disrupts normal temperature and rainfall patterns across many regions, according to the WMO.

El Nino can bring severe drought to some regions, heavy rainfall and flooding to others, and increased heat across large parts of the world.